Ultra rapid cycle portable oxygen concentrator

ABSTRACT

Lightweight, portable oxygen concentrators that operate using an ultra rapid, sub one second, adsorption cycle based on advanced molecular sieve materials are disclosed. The amount of sieve material utilized is a fraction of that used in conventional portable devices. This dramatically reduces the volume, weight, and cost of the device. Innovations in valve configuration, moisture control, case and battery design, and replaceable sieve module are described. Patients with breathing disorders and others requiring medical oxygen are provided with a long lasting, low cost alternative to existing portable oxygen supply devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/499,943 filed Apr. 3, 2012, now U.S. Pat. No. 8,894,751 issued Nov.25, 2014, which is a U.S. national phase patent application under 35U.S.C. §371 of International Patent Application No. PCT/US2010/51419filed Oct. 5, 2010, which claims priority under PCT Article 8 to U.S.Application No. 61/264,069 filed Nov. 24, 2009 and U.S. Application No.61/248,712 filed Oct. 5, 2009, each of which is incorporated herein byreference in its entirety.

REFERENCE TO GOVERNMENT GRANTS

Portions of the disclosure herein may have been supported in part bygrants from the National Science Foundation/Small Business InnovativeResearch Grant No. 0419821 and the National Institutes of Health/SmallBusiness Technology Transfer Research Grant No. 1 R41 HL080825-01. TheUnited States Government may have certain rights in this application.

FIELD OF THE INVENTION

The invention relates generally to devices, systems, and methods forcarrying out adsorption processes for separating and purifying fluidmixtures and, more particularly, to portable devices, systems, andmethods for separation and purification processes employing advancedmolecular sieve materials, especially for concentrating medical oxygen.

BACKGROUND OF THE INVENTION

The supply of therapeutic oxygen to patients in homes and otherresidential settings is an important and growing segment of the healthcare industry. Oxygen can be supplied to a patient by liquid orcompressed oxygen with an appropriate vaporization or pressureregulation system and a gas delivery cannula. Alternatively, oxygen canbe supplied by the generation of oxygen using a small onsite airseparation device or medical oxygen concentrator located near thepatient that delivers the generated oxygen via a cannula.

Respiratory oxygen usage rates typically range up to 3 LPM (liters perminute at 22° C. and 1 atmosphere pressure) for ambulatory patients withrelatively low oxygen requirements, up to 5 LPM for patients with moreserious respiratory problems and possibly limited mobility, and incertain cases up to 10 LPM for those with the most serious respiratoryproblems and more limited mobility. A patient initially may require ahigher oxygen supply rate during an illness and later may require lessoxygen as recovery is achieved. Alternatively, a patient may requireincreasing oxygen rates as a chronic condition worsens. A conserver maybe used to provide oxygen flow only when the patient inhales, therebyreducing the amount of oxygen required by eliminating the supply ofoxygen that is wasted when the patient exhales.

Portable medical oxygen concentrators often are preferred over liquid orcompressed oxygen supply systems in home and residential settings, andsmall air separation devices for these applications are being developedby numerous vendors in the home health care field. Patients typicallyare encouraged to be ambulatory whenever possible to increase theeffectiveness of oxygen therapy and improve their overall health. Theportability of a medical oxygen concentrator therefore is an importantfeature allowing the patient to move about easily and comfortably. Tomaximize portability and ease of use, the medical oxygen concentratormust be designed to have minimum weight and compact dimensions. Patientambulation time can be maximized by the use of a conserver.

There is a need in the home health care field for an improved,lightweight, battery-powered portable oxygen concentrator for deliveringoxygen product to ambulatory patients. These patients typically requirea concentrator that can generate up to about 3 LPM of oxygen on acontinuous basis and that includes a built-in conserver that maximizesambulation time. The invention is directed to these, as well as other,important ends.

SUMMARY OF THE INVENTION

The invention provides lightweight, portable oxygen concentrators thatoperate using an ultra rapid, sub one second, adsorption cycle based onadvanced molecular sieve materials. The amount of sieve materialutilized is a fraction of that used in conventional portable devices.This dramatically reduces the volume, weight, and cost of the device.Innovations in valve configuration, moisture control, case and batterydesign, and replaceable sieve module are described. Patients withbreathing disorders and others requiring medical oxygen are providedwith a long lasting, low cost alternative to existing portable oxygensupply devices.

In one embodiment, the invention is directed to removable modules for aportable oxygen concentrator, comprising:

at least one cartridge, comprising:

a housing having a feed end and a product end;

at least one input port for incoming air flow in said feed end;

a feed end plug;

a diffusion channel in said feed end;

an optional rupture plate for said input port;

at least one adsorbent bed contained in said housing, wherein saidadsorbent bed comprises at least one molecular sieve material having anaverage particle size of about 60 μm to 180 μm and having asubstantially spherical shape;

wherein said adsorbent bed has an aspect ratio of length to diameter ofless than about 6;

an optional fibrous pad positioned at either end or both ends of saidadsorbent bed;

at least one output port for an oxygen-enriched product flow in saidproduct end; and

a product end plug comprising a gas flow controls and at least onecollection channel;

at least one enriched-oxygen product tube, comprising:

-   -   an input end plug;    -   an oxygen input port in said input end plug;    -   an output end plug;    -   an oxygen output port in said output end plug; and    -   an optional rupture plate for said oxygen output port; and

a product end block comprising at least one passageway for transport ofsaid oxygen-enriched product;

wherein said at least one cartridge and said at least enriched-oxygenproduct tube are connected to said product end block.

In another embodiment, the invention is directed to manifolds forportable oxygen concentrators, comprising:

a solid body having a passageway for transporting fluid;

a connection for fresh air from a compressor to said passageway fortransporting fluid;

a 2-way compressor valve within said connection for fresh air;

at least one first connection from said passageway to a cartridgecomprising an adsorbent bed for separating air components;

at least one second connection to said passageway from anoxygen-enriched product source;

a valve within said second connection;

two 3-way adsorbent bed valves within said passageway for transportingfluids positioned on both sides of said first connection;

at least one exhaust port;

an optional piercing mechanism attached to said solid body at said onefirst connection; and

an optional piercing mechanism attached to said solid body at said onesecond connection.

In yet other embodiments, the invention is directed to portable oxygenconcentrators, comprising:

at least one removable module described herein;

a compressor;

an optional moisture control unit comprising a getter material formoisture positioned between said compressor and said inlet port of saidremovable module;

a manifold to control gas flow into and out of said removable modulecomprising:

-   -   a solid body having a passageway for transporting fluid;    -   a connection for fresh air from a compressor to said passageway        for transporting fluid;    -   a 2-way compressor valve within said connection for fresh air;    -   at least one first connection from said passageway to a        cartridge comprising an adsorbent bed for separating air        components;    -   at least one second connection to said passageway from an        oxygen-enriched product source;    -   a valve within said second connection;    -   two 3-way adsorbent bed valves within said passageway for        transporting fluids positioned on both sides of said first        connection;    -   at least one exhaust port;    -   an optional piercing mechanism attached to said solid body at        said one first connection; and    -   an optional piercing mechanism attached to said solid body at        said one second connection;

at least one optional moisture control unit;

an optional oxygen sensor; and

at least one battery cell.

In other embodiments, the invention is directed to systems, comprising:

a portable oxygen concentrator described herein;

a docking station; and

a battery recharger.

In another embodiment, the invention is directed to methods of producingan oxygen-enriched gas flow, comprising:

compressing an ambient air flow comprising oxygen and nitrogen to form acompressed air flow;

transporting said compressed flow through an adsorbent bed to adsorb atleast a portion of said nitrogen to form an oxygen-enriched gas flow;and

removing said oxygen-enriched gas flow to form an oxygen-enrichedproduct;

wherein the pressure drop across said adsorbent bed is less than about50 kPa.

The method may further comprise the step of desorbing from saidadsorbent bed said portion of said nitrogen. The method may furthercomprise the step of exhausting said portion of said nitrogen desorbedfrom said adsorbent bed. The method may further comprise the step ofcollecting said oxygen-enriched product. The oxygen-enriched product isdelivered to a recipient in need thereof.

In another embodiment, the invention is directed to methods of reducingthe power requirement of a zirconium-based oxygen sensor, comprising:

intermittently operating said zirconium-based oxygen sensor.

In another embodiment, the invention is directed to methods of reducingthe power requirement of a zirconium-based oxygen sensor comprising aheater and a heater control, said method comprising:

modulating the pulse-width of said heater control of said heater duringoperation of said zirconium-based oxygen sensor.

In another embodiment, the invention is directed to methods ofincreasing the lifetime of an electrochemical oxygen sensor in aportable oxygen concentrator, comprising:

periodically turning gas flow off to said electrochemical oxygen sensorin said portable oxygen concentrator.

In another embodiment, the invention is directed to portable oxygenconcentrator systems, comprising:

a portable oxygen concentrator module having a first partial handleportion and at least one removable module having an enriched-oxygenproduct tube and at least one cartridge comprising adsorbent; and

a battery pack module having a second partial handle portion;

wherein said battery pack module releasably connects to said portableoxygen concentrator module;

wherein said first partial handle portion and said second partial handleportion align to form a single integrated handle; and

wherein said first partial handle portion inserts and secures saidremovable module in said portable oxygen concentrator system by leveraction.

In another embodiment, the invention is directed to methods of reducingmoisture content and increase throughput in a portable oxygenconcentrator providing an enriched-oxygen product, comprising:

providing a moisture control unit comprising a getter material thatscavenges moisture when said portable oxygen concentrator is notoperating;

providing compressed air comprising oxygen and nitrogen to an adsorbentbed to adsorb said nitrogen and produce said enriched-oxygen product;

wherein said getter material is gas impervious to prevent contaminationof said enriched-oxygen product by said nitrogen in said compressed gas.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a cross-sectional view of the removable module 49 and themanifold 12 portions of a portable oxygen concentrator 43.

FIG. 1A is a schematic diagram of a removable module 49 having twocartridges 18, an enriched oxygen product tube 22, and inlet particulateair filter 61.

FIG. 2 is a vertical cross-section of the removable module 18 showing arupture plate 3 covering the feed end plug 4 to seal the adsorbent bed 8and prevent contamination, especially contamination from moisture,during storage prior to use.

FIG. 3 is a vertical cross-section of the piercing mechanism 15 andmodule connections to the manifold 13 with the rupture plate 3 (shownafter piercing by the piercing mechanism 15).

FIG. 3A is a vertical cross-section of the valving in the manifold 13 ofone embodiment. FIG. 3B is a top view of the valving in the manifold 13of one embodiment.

FIG. 4 is a plan view of the rupture plate 3 showing a pre-weakenedpattern 7, which permits easy opening with the piercing mechanism 15(not shown).

FIG. 5 is a plan view of the removable module 18 showing product endplug 12, center feed hole 19, and collection channel 10.

FIGS. 6A, 6B, and 6C are back, top and bottom views, respectively, ofthe battery pack configured with fifteen cells (eight on top layer,seven on bottom layer).

FIG. 7 is an exploded perspective view of the fifteen cell battery packwith the battery cells, PCM unit, and back of the battery case.

FIG. 8 is a side view of a portable oxygen concentrator system having abattery pack module and portable oxygen concentrator module.

FIG. 9 is a block diagram of an oxygen sensor electronics.

FIG. 10 is an illustration of the oxygen sensor signal timing.

FIG. 11 is a schematic view of the moisture control unit of the portableoxygen concentrator.

FIGS. 12A and 12B are scanning electron micrographs images detailing theregular, spherical nature of the adsorbents employed in the invention.FIG. 12A shows the individual adsorbent particle beads. FIG. 12B showsthe small zeolite crystal component parts of the individual adsorbentparticle beads.

FIG. 13 is a plot of % oxygen purity as a function of time in hours toshow the drop in oxygen purity (input air had a relative humidity of75%).

FIG. 14 is a plot of productivity as a function of cycle time in secondsfor a 0.7 inch ID×3 inch long absorbent bed (contactor).

FIG. 15 is a plot of % oxygen purity as a function of time in hours toshow the drop in oxygen purity using adsorbent beds that hold about 0.95g of adsorbent.

FIG. 16 is a plot of % oxygen purity (projected and measured) as afunction of time in hours to show the drop in oxygen purity usingadsorbent beds that hold about 10 g of adsorbent.

FIG. 17 is a plot showing the maximum cycle rate (in Hz) as a functionof adsorbent mass (in grams) achieving at least 85% oxygen purity.

FIG. 18 is a block diagram of some of the components of an embodiment ofthe portable oxygen concentrator, including removable module 49,manifold 13, compressor 2, moisture control unit 24, oxygen sensor 25,conserver 31, cannula 30 (not shown), battery pack 40, and electroniccontrols 60.

Part Number Description  1 Housing  1A Feed end of housing  1B Productend of housing  2 Compressor  3 Rupture plate  4 Feed end plug  5Diffusion channel  6 Fibrous pad  7 Pre-weakened pattern  8 Adsorbentbed  9 Fibrous pad 10 Collection channel 11 Gas flow control orifice 12Product end plug 13 Manifold 14 Scal 15 Piercing mechanism 16 Input port17 Output port 18 Cartridge 19 Center feed hole 20 Passageway forcompressed fresh air 21 Connection for an enriched oxygen product 22Enriched oxygen product tube 23 Exhaust port 24 Moisture control unit 25Oxygen sensor 26 Battery cell 27 Outer chamber 28 Inner chamber 29Muffler 30 Cannula 31 Conserver 32 Docking station 33 Battery recharger34 Battery cell 35 Battery pack case 36 Protection circuit module 37Back plate 38 Battery pack handle 39 Portable oxygen concentrator handle40 Battery pack module 41 Tabs 42 Recessed female connectors forpositive and negative terminals 43 Portable oxygen concentrator module(without battery pack module) 44 Back pressure device 45 Entry port(FIG. 11) 46 Exit port (FIG. 11) 47 2-way compressor valve 48 3-wayadsorbent bed valve 49 Removable module 50 Passageway to/from cartridge51 Passageway from enriched-oxygen product tube 22 52 Oxygen input portin enriched oxygen product tube 22 53 Oxygen output port in enrichedoxygen product tube 22 54 Manifold passageway 55 Solid body 56 Valve 57Input end plug in enriched-oxygen product tube 22 58 Output end plug inenriched-oxygen product tube 22 59 Product end block 60 Electroniccontrols 61 Inlet particulate air filter

DETAILED DESCRIPTION OF THE INVENTION

The invention provides lightweight, portable oxygen concentrators thatoperate using an ultra rapid, sub one second, adsorption cycle based onadvanced molecular sieve materials. The amount of sieve materialutilized is a fraction of that used in conventional portable devices.This dramatically reduces the volume, weight, and cost of the device.Innovations in valve configuration, moisture control, case and batterydesign, and replaceable sieve module are described. Patients withbreathing disorders and others requiring medical oxygen are providedwith a long lasting, low cost alternative to existing portable oxygensupply devices.

Definitions

The following definitions are provided for the full understanding ofterms used in this specification.

As used herein, the article “a” means “at least one”, unless the contextin which the article is used clearly indicates otherwise.

As used herein, the terms “separation” and “separating” mean the act orprocess of isolating or extracting from or of becoming isolated from amixture (a composition of two or more substances that are not chemicallycombined).

As used herein, the terms “purification” and “purifying” means the actor process of separating and removing from anything that which is impureor noxious, or heterogeneous or foreign to it.

As used herein, the term “fluid” refers to a continuous amorphoussubstance that tends to flow and to conform to the outline of itscontainer, including a liquid or a gas, and specifically includessolutions (where solids dissolved in the liquid or gas) and suspensions(where solids are suspended in liquid or gas).

As used herein, the term “portable” refers to a device that may becapable of being carried or moved. Preferably, the term refers to adevice that may be carried by an adult or child with little or noeffort. However, the term also refers to a device that is notpermanently affixed to a permanent structure and is of sufficiently lowmass and bulk that it may be easily transported as part of a vehicle ortransportation device. Preferably, the portable oxygen concentrators ofthe invention weigh less than about 5 kg.

As used herein, the term “chamber” refers to a three-dimensional volumehaving an generally solid outer surface that is generally elliptical orcircular in cross-sectional shape.

The term “adsorbent” or “adsorbent contactor” refers to an adsorbent ora membrane containing an adsorbent.

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the drawings and theexamples. This invention may, however, be embodied in many differentforms and should not be construed as limited to the embodiments setforth herein. In addition and as will be appreciated by one of skill inthe art, the invention may be embodied as a product, method, system orprocess.

In one embodiment, the invention is directed to removable modules for aportable oxygen concentrator, comprising:

at least one cartridge, comprising:

-   -   a housing having a feed end and a product end;    -   at least one input port for incoming air flow in said feed end;    -   a feed end plug;    -   a diffusion channel in said feed end;    -   an optional rupture plate for said input port;    -   at least one adsorbent bed contained in said housing, wherein        said adsorbent bed comprises at least one molecular sieve        material having an average particle size of about 60 μm to 180        μm and having a substantially spherical shape;    -   wherein said adsorbent bed has an aspect ratio of length to        diameter of less than about 6;    -   an optional fibrous pad positioned at either end or both ends of        said adsorbent bed;    -   at least one output port for an oxygen-enriched product flow in        said product end; and    -   a product end plug comprising a gas flow controls and at least        one collection channel;

at least one enriched-oxygen product tube, comprising:

-   -   an input end plug;    -   an oxygen input port in said input end plug;    -   an output end plug;    -   an oxygen output port in said output end plug; and    -   an optional rupture plate for said oxygen output port; and

a product end block comprising at least one passageway for transport ofsaid oxygen-enriched product;

wherein said at least one cartridge and said at least enriched-oxygenproduct tube are connected to said product end block.

In another embodiment, the invention is directed to manifolds for aportable oxygen concentrator, comprising:

a solid body having a passageway for transporting fluid;

a connection for fresh air from a compressor to said passageway fortransporting fluid;

a 2-way compressor valve within said connection for fresh air;

at least one first connection from said passageway to a cartridgecomprising an adsorbent bed for separating air components;

at least one second connection to said passageway from anoxygen-enriched product source;

a valve within said second connection;

two 3-way adsorbent bed valves within said passageway for transportingfluids positioned on both sides of said first connection;

at least one exhaust port;

an optional piercing mechanism attached to said solid body at said onefirst connection; and

an optional piercing mechanism attached to said solid body at said onesecond connection.

In another embodiment, the invention is directed to portable oxygenconcentrators, comprising:

at least one removable module of claim 1;

a compressor;

an optional moisture control unit comprising a getter material formoisture positioned between said compressor and said inlet port of saidremovable module;

a manifold to control gas flow into and out of said removable modulecomprising:

-   -   a solid body having a passageway for transporting fluid;    -   a connection for fresh air from a compressor to said passageway        for transporting fluid;    -   a 2-way compressor valve within said connection for fresh air;    -   at least one first connection from said passageway to a        cartridge comprising an adsorbent bed for separating air        components;    -   at least one second connection to said passageway from an        oxygen-enriched product source;    -   a valve within said second connection;

two 3-way adsorbent bed valves within said passageway for transportingfluids positioned on both sides of said first connection;

at least one exhaust port;

an optional piercing mechanism attached to said solid body at said onefirst connection; and

an optional piercing mechanism attached to said solid body at said onesecond connection;

at least one optional moisture control unit;

an optional oxygen sensor; and

at least one battery cell.

To more fully understand the invention, the various embodiments will bedescribed with respect to the figures.

FIG. 18 is a block diagram of some of the components of an embodiment ofthe portable oxygen concentrator, including the removable module 49,manifold 13, compressor 2, moisture control unit 24, oxygen sensor 25,conserver 31, cannula 30 (not shown), battery pack 40, and electroniccontrols 60.

FIG. 1 is a cross-sectional view of the removable module 49 and themanifold 12 portions of a portable oxygen concentrator 43 showingcompressed air flow from a compressor 20 (not shown).

The removable module 49 in the embodiment of FIG. 1 has two cartridges18. The cartridge 18 has a housing 1 having a feed end 1A and a productend 1B; at least one input port 16 for incoming air flow in said feedend 1A; a feed end plug 4; a diffusion channel 5 in said feed end 1A; anoptional rupture plate 3 for said input port 16; and at least oneadsorbent bed 8 contained in said housing 1, at least one output port 17for an oxygen-enriched product flow in said product end 1B; and aproduct end plug 12 comprising a gas flow controls 11 and at least onecollection channel 10. The adsorbent bed comprises at least onemolecular sieve material having an average particle size of about 60 μmto 180 μm and having a substantially spherical shape. The adsorbent bedhas an aspect ratio of length to diameter of less than about 6. Optionalthe cartridge has fibrous pad 6, 9 positioned at either end or both endsof said adsorbent bed.

The removable module 49 in the embodiment of FIG. 1 has at least oneenriched-oxygen product tube 22, which has an input end plug 57; anoxygen input port 52 in said input end plug 57; an output end plug 58;an oxygen output port 53 in the output end plug 58; and an optionalrupture plate 3 for the oxygen output port.

The removable module 49 in the embodiment of FIG. 1 has a product endblock 59 has passageway 19 for transport of said oxygen-enrichedproduct. Each cartridge 18 and the enriched-oxygen product tube 22 areconnected to said product end block 59.

The portable oxygen concentrator in the embodiment of FIG. 1 also has amanifold 13 to control gas flow into and out of the removable module 18.The manifold has a solid body 55 having a passageway for transportingfluid 54. Within the solid body, there is also a connection for freshair 20 from a compressor 2 to the passageway for transporting fluid 54with a 2-way compressor valve 47 within the connection for fresh air 20,a first connection 50 from the passageway to a cartridge, a secondconnection 51 to the passageway from an oxygen-enriched product source.Also, there is a valve 56 within the second connection 51. Two 3-wayadsorbent bed valves 48 are found within the passageway for transportingfluids and are positioned on both sides of said first connection 50. Thepassageway leads to an exhaust port 23. The manifold optionally has apiercing mechanism 15 attached to the solid body at the first connectionand an optional piercing mechanism 15 attached to the solid body at thesecond connection.

FIG. 1A is a schematic diagram of a removable module 49 having twocartridges 18, an enriched oxygen product tube 22, and inlet particulateair filter 61.

FIG. 2 is a vertical cross-section of the cartridge 18 of the removablemodule 49 of one embodiment of the invention showing a rupture plate 3covering the feed end plug 4 to seal the adsorbent bed 8 and preventcontamination, especially contamination from moisture, during storageprior to use. Housing 1 has a feed end 1A (which is also the exhaust endwith respect to the nitrogen exhausted from the device) and a productend 1B (with respect to the oxygen-enriched product gas). In the feedend (i.e., where the compressed fresh air is received into removablemodule), there is at least one input port 16 for incoming air flow insaid feed end, a feed end plug 4 (which can be made from such materialsas polymers or lightweight metals), a diffusion channel 5, and anoptional rupture plate 3 for said input port. In the product end (i.e.,where one of the fluid flows in enriched in oxygen after passing throughthe adsorbent beds described herein), there is a product end plug 12comprising a gas flow control orifice 11, at least one collectionchannel 10, and at least one passageway (center feed hole 19) fortransport of said fluid product, and an optional rupture plate 3 forsaid output port 17. Housed within the removable module is at least oneadsorbent bed 8 contained in said housing 1, wherein said adsorbent bedcomprises at least one molecular sieve material having an averageparticle size of about 60 μm to 180 μm and having a substantiallyspherical shape. The adsorbent bed has an aspect ratio of length todiameter of less than about 6. Optionally, a fibrous pad 6, 9 may bepositioned at either end of said adsorbent bed.

FIG. 3 is a vertical cross-section of the piercing mechanism 15 andmodule connections to the manifold 13 with the rupture plate 3 (shownafter piercing by the piercing mechanism 15). As the removable module 18is moved toward the piercing mechanism on the manifold 13, the ruptureplate 3 is pierced thereby permitted compressed fresh air from thecompressor 2 (not shown) to enter the feed end 1A of the removablemodule 18 through the feed end plug 4 into the diffusion channel 5through the fibrous pad 6 and finally into the adsorbent bed 8. A seal14, such as an O-ring or gasket, seals the connection.

FIG. 3A is a vertical cross-section of the valving in the manifold 13 inan embodiment having two cartridges 18 and a single enriched oxygenproduct tube 22. FIG. 3B is a top view of the valving in the manifold13. In this embodiment, there are two 3-way valves 48 to control gasflow into and out of the adsorbent beds and single 2-way valve 47 tocontrol the flow of compressed air from the compressor 2 (not shown)throught the connection 20. In certain embodiments, the workingcomponents of the valves are integrated into the solid body 55 of themanifold 13 rather than mounted to it. The working components of thevalves (i.e., the poppets, spools, or piezoelectric elements) areintegrated into the solid body 55 to make it a more compact, lighterunit and the gas flow pathways 50, 51, and 54 are also contained withinthe manifold as in other arrangements where the valves are mounted ontothe manifold. In certain embodiments, solenoids (not shown) actuate thevalves and may either be contained within solid body 55 or may bemounted to it.

FIG. 4 is a plan view of the rupture plate 3 showing a pre-weakenedpattern 7, which permits easy opening with the piercing mechanism 15(not shown).

FIG. 5 is a plan view of the removable module 18 showing product endplug 12, center feed hole 19, and collection channel 10.

The portable oxygen concentrators (POC) of the various embodiments aredesigned to operate using ultra rapid cycle pressure swing adsorptionwhere the cycles are less than one second in duration. Traditional POCsoperate using cycles that are several seconds long. Pressure swingadsorption systems typically use adsorbent beds filled with sphericalparticles of the molecular sieve materials, especially zeolites, whichpreferentially adsorb nitrogen when they are filled with pressurizedair, thus producing an oxygen-enriched product. When the beds aredepressurized, the nitrogen is desorbed. Since the adsorption capacityfor nitrogen of the beds is limited, shortening the cycle isadvantageous in that it allows more output to be produced from a smallerquantity of adsorbent. Typical POCs use adsorbent beds that containapproximately 0.5 kilograms of adsorbent. The ultra rapid cycleoperation of the devices of the various embodiments allows the use ofadsorbent beds that contain less than about 50 grams of adsorbent. Thisdrastic reduction in the amount of adsorbent material required allowsfor a significant savings in mass and volume of the portable oxygenconcentrator.

To operate using cycles of less than one second duration, advancedmolecular sieve materials are required. Smaller particles are utilizedto allow for more rapid diffusion of gas through the porous structure ofthe particle. The molecular sieve particles used in the invention rangein diameter from about 60 μm to about 180 μm, and the preferred diameterrange is between about 80 μm and about 120 μm. Conventional technologyuses particles that range in size from about 0.4 mm to about 0.8 mm. Thesmaller size of the adsorbents employed in the various embodimentsallows gases to diffuse in and out of the beads very rapidly so cycletimes of 0.15 seconds are possible. This is at least ten (10) timesfaster than any cycle time used in any commercial separations device.Fast cycle times equate to smaller amounts of adsorbent being requiredto process the same amount of gas.

The relationship between cycle rate and adsorbent quantity required isroughly an inverse relationship, i.e., doubling cycle rate from 1 cycleper second to 2 cycles per second means that the typical separationssystem would go from using 0.5 kg of adsorbent to using 0.25 kgadsorbent. Conventional portable oxygen concentrators typically useabout 300 grams to about 450 grams of adsorbent in a system thatproduces about 750 ml to about 1000 ml per minute of oxygen. Theportable oxygen concentrator of the invention can use as little as about5 grams to about 30 grams to produce the same amount of oxygen perminute. The considerable weight and volume reduction may be used todecrease the device size and weight, or to increase the size and volumeof the battery, thereby providing longer operating time.

The particles must also be highly spherical, because any irregularity intheir shape greatly increases the pressure drop through the adsorbentbed. FIGS. 12A and 12B are scanning electron micrographs imagesdetailing the regular, spherical nature of the adsorbents employed inthe invention. FIG. 12A shows the individual adsorbent particle beads.FIG. 12B shows the small zeolite crystal component parts of theindividual adsorbent particle beads.

Most currently available molecular sieve materials for air separationhave a lower limit diameter of about 560 micrometers. This diameterlimits how fast gases can diffuse into and out of the adsorbent bead.This is why the fastest cycle time for commercially available oxygenconcentrators is about 4 seconds. Most researchers believed that makingthe beads smaller would increase tortuosity to the point that an energywasting pressure drop would be introduced. The present research showedthat this was the case with irregular shaped adsorbents, but highlyspherical beads, as small as 100 micrometers in diameter did notintroduce too large a pressure drop as long as a certain sieve bedlength to cycle rate ratio was maintained. This ratio is about 10 cm bedlength to one second of cycle time. For example, a 0.5 second cycle timewould require a 5 cm bed length. If for a given cycle rate, a lagerthroughput is required, the sieve beds may be paralleled. For example, apressure swing adsorption system having two beds that operate inalternating fashion, having dimensions of 7 cm long by 2 cm in diameter,can produce about 750 ml per minute of 94% purity oxygen at a cycle timeof 0.7 seconds. If a production rate of 1500 ml per minute is required,the same cycle rate may be used by paralleling with two additional sievebeds having parallel inlet and outlet ports. Thus an oxygen concentratorhaving any desired output can be manufactured.

For practical reasons, there may be a minimum bed size and maximum cyclerate for a given application. Having more sieve material equates to lessfrequent sieve bed exchanges. It has been discovered that two 7 cm longby 2 cm diameter adsorbent beds strike the best balance between devicesize reduction and frequency of sieve bed replacement.

The molecular sieve material used in the module and portable oxygenconcentrator of the invention imposes limitations upon the dimensions ofthe adsorbent bed. Beds longer than about 12 centimeters in length andabout 2.5 centimeters in diameter are impractical due to excessivepressure drop through the bed. The preferred bed size is about 1.7 toabout 2 cm in diameter, and about 7 cm to about 8 cm in length. Thepreferred ratio of the bed length to bed diameter is about 4.3:1. Eachadsorbent bed is capable of producing a maximum of between 350 and 500milliliters per minute of oxygen-enriched product of at least 85%purity. The beds are preferably used in pairs, and if more output isdesired, multiple beds or sets of beds may be used.

Molecular sieve materials, such as zeolites, which are useful asadsorbents, are highly susceptible to contamination by water, andbecause of this and other factors such as particle attrition, theperformance of oxygen concentrators degrades over time. Once aconcentrator's performance has dropped to the extent that it is nolonger able to provide adequate oxygen output (typically at least theequivalent of 2 liters per minute of 85% oxygen), the concentrator isgenerally replaced or the adsorbent is replaced by the manufacturer or areseller. The life of the adsorbent is often the limiting factor in thelife of the device. It is therefore advantageous to have an adsorbentthat is replaceable by the user. The invention features a removable andreplaceable adsorbent module that is designed to be patient friendly andrequire very little physical strength or dexterity to install. Incertain embodiments, the module features two or more adsorbent beds,inlet ports for air that lead to each of the beds, an outlet port forthe oxygen enriched product, and a product-end block that contains gasflow controls and passageways.

In a pressure swing adsorption system, the majority of the product gasis allowed to exit the system as output, and some of it is allowed toflow into the product end of the bed that is in its desorption stage inorder to drive the desorbed nitrogen out of the bed and flood it withoxygen-enriched gas. Conventional oxygen concentrators achieve this byusing a check valve to control the flow out of the bed, and an orificeto allow purge flow back into the bed. The invention simplifies thisarrangement by using only an orifice whose diameter is selected tocreate sufficient pressure in the beds, control the output flow, andallow adequate purge flow. It is possible that this orificepreferentially allows free flow in one direction, while restricting itto a certain degree in the other direction. The orifices may becontained in the product-end block 59 of the module, as may passages toallow air to flow between the adsorbent beds and to the oxygen outputport 17.

The module must be sealed to prevent moisture and other contaminantsfrom entering the adsorbent during storage and installation. The portsare covered with rupture plates that are constructed of a material thatis easily pierced, such as a plastic film or an aluminum foil. Inpreferred embodiments, the rupture plates are adhered to the top of themolecular sieve bed. The rupture plates are preferable pre-weakened (bydie-stamping, laser ablation, or some other suitable method) to ensurethat they rupture in a predictable pattern.

When the module is installed into the oxygen concentrator, it connectsto a manifold that controls the flow of gas in and out of the module. Incertain embodiments, the manifold has a piercing mechanism thatpunctures the rupture plates as the module is installed. The piercingmechanism includes projections that are designed to pierce the ruptureplates and push the rupture plate material aside so that it does notobstruct flow in/out of the module. In preferred embodiments, the modulehas sockets into which the piercing mechanism fits that are designed tominimize head space (dead volume). In certain embodiments, the interfacebetween the module and the manifold is sealed with a flexible seal suchas an o-ring or rubber gasket. After the module is in place,installation is completed by closing a mechanism that applies pressureto the module and holds it tight against the seal to ensure an airtightfit. In certain embodiments, the mechanism has a hinged “door” thatcloses against the module and a latch to hold the “door” closed. Thisdoor may also comprise the handle of the device, as shown in FIG. 8.

The gas flow manifold of the oxygen concentrator includes a connectionfor fresh air from the compressor, a connection for the oxygen tubewhich leads to the oxygen reservoir, and exhaust ports, which areconnected to an optional muffler. In certain embodiments, a 3-waysolenoid valve is mounted in or on the manifold to control the flow intoand out of each of the adsorbent beds in the module. In certainembodiments, a 2-way valve is used to control the flow of pressure airfrom the compressor.

In certain embodiments having two cartridges with adsorbent beds, theoperating cycle of the valves is as follows:

-   (1) The compressor valve opens, as does the 3-way valve connected to    the first adsorbent bed, and the bed is pressurized.-   (2) The compressor valve closes, and the 3-way valve connected to    the second adsorbent bed opens while the first adsorbent bed valve    remains open. This step allows pressurized, oxygen-enriched gas from    the first bed to partially pressurize the second bed. This step is    preferred because it decreases the amount of compressed air needed,    thereby increasing the energy efficiency of the device.-   (3) The 3-way valve connected to the first bed closes, and the first    bed 1 enters its exhaust/desorption phase. The compressor valve    opens, and the second bed is fully pressurized.-   (4) Pressure from the second bed is used to partially pressurize the    first bed (this step is the reverse of step 2).    The cycle then repeats.

The adsorbent/filter module includes a novel design that eliminates thesprings commonly used to keep the bed packed tightly. With reference toFIG. 1, a housing 1, preferably in the form of a round tube constructedof aluminum, plastic, or other lightweight material, contains the bed ofadsorbent material. A compliant, fibrous pad 6, 9 is placed at eitherend of the bed. The pad serves at least three purposes:

-   (1) to act as a filter and prevent microscopic dust particles    created by attrition of the adsorbent material from escaping the    bed;-   (2) to act as a cushion to protect the adsorbent particles; and-   (3) to restrain the bed.    The pads 6, 9 are held in place by plugs 4, 12 that are an    interference fit with the housing. The feed end plug 4 contains the    socket into which the piercing mechanism 15 fits (as shown in FIG.    3), and the product end plug 12 contains the air outlet and in one    possible embodiment the flow control orifice 11. The surfaces of the    plugs that contact the pads may have passageways cut in them to    promote diffusion of gas across the surface of the bed, or    alternatively, a diffusion plate may be inserted between the plugs    and the pads. The assembly is pressed together using a mechanical    press to ensure that the plugs are seated firmly against the pads    and the adsorbent beds, effectively locking the adsorbent particles    in place. Eliminating any movement of the adsorbent particles in    this fashion greatly reduces attrition.    Absorbent Beds

The absorbent beds comprise at least one molecular sieve material havingan average particle size of about 60 μm to 180 μm and having asubstantially spherical shape. Preferred molecular sieve materials arealuminophosphate and silicoaluminophosphate (zeolite) types, and metalsubstituted aluminophosphate and silicoaluminophosphate (zeolite)molecular sieves (including, but not limited to, Li⁺, Na⁺, K⁺, Ca²⁺,Ag¹⁺ and/or Mg²⁺-substituted aluminophosphate and silicoaluminophosphatemolecule sieves), especially as part of a polymer matrix. Such zeoliteadsorbents are available from Arkema Inc., Philadelphia, Pa., USA.

The sorbent structure may further comprise at least one support. Incertain embodiments, at least a portion of the sorbent is adhered to orembedded in the support. Preferably, the support is a series ofmicro-channels, laminar, a porous electrode; a series of concentriclayers, or a combination thereof.

Suitable supports for use in the methods, devices, and systems of theinvention include, but are not limited to, natural clay, calcined clay,modified clay, chemically treated clay, chemically modified clay,smectite clay, kaolin clay, sub-bentonite clay, kaolin-halloysite clay,kaolin-kaolonite clay, kaolin-nacrite clay, kaolin-anauxite clay, binarymatrix material, tertiary matrix material, silica-thoria,silica-alumina, silica-alumina-thoria, silica-alumina-zirconia, fibrousmaterial, colloidal silica material, colloidal alumina material,colloidal zirconia material, colloidal mixture, surface modifiedamorphous silicon dioxide nanoparticles, hydrated magnesium aluminumsilicate, thermoplastic polymer, thermosetting polymer, ferrous support,non-ferrous support, electrically-conductive support, dielectricsupport, electromagnetic receptor, or a combination thereof. The supportmay be applied by sintering, pyrolysis, slurrying, vapor deposition,casting, electro-spraying, electrophoretic deposition, extrusion, laserdeposition, electron beam deposition, silk screening, photo-lithographydeposition, electrostatic self-assembly, high aspect ratiomicromachining, LIGA-formation, atomic layer deposition, casting,stamping, or a combination thereof

In certain preferred embodiments, each unit comprising sorbent structuremay utilize different sorbents, wherein each of the sorbents isselective for a different component of the same or different mixture.

In certain embodiments, a combination of different molecular sievematerial may be employed.

Moisture Management

The use of very small amounts of adsorbent has weight advantages butalso creates challenges. All nitrogen selective adsorbents can berendered non-functional if contaminated with moisture. Larger systemshave sufficient quantities of adsorbent that moisture contamination isnot a problem over the 3-year average device lifetime. Smaller devicesmay require periodic replacement of the adsorbent material. Because sucha small quantity of adsorbent is used in the embodiments of the portableoxygen concentrator, moisture management becomes a significant issue.Two approaches may be employed to mitigate these problems in the variousembodiments.

One approach is the use, for example, of an alumina or other adsorbentbarrier between the compressed inlet air and the ultra-dry oxygenenriched gas (product). Moisture diffuses toward the oxygen side becauseof pressure differentials and H₂O partial pressure differentials(equilibrium driven). Also, a second barrier between the compressedinlet gas (air) and the nitrogen enriched waste gas may be used. Themoisture is driven toward the nitrogen waste gas side via a pressuredifferential mechanism. The barrier material (unlike a membrane) is notgas permeable.

In one embodiment, co-axial containers 24 are configured with the outerchamber 27 made of a lightweight metal, such as aluminum (27 in FIG.11), and the inner chamber (28 in FIG. 11) comprising a water permeablematerial, described below.

In operation, feed air (directly from the compressor outlet) enters theouter chamber 27 on container 24, labeled A, and exits to a secondcontainer 24 of similar design, labeled B. Dry product oxygen from theadsorbent bed(s) 8 is directed into the inner chamber of A 28 and exitsto the conserver 31 and/or a backpressure device 44. Waste nitrogen fromthe adsorbent bed 8 is directed through the inner chamber 28 of B andexits to an exhaust outlet 23 (not shown). Throughout operation of thedevice, a pressure differential exists across the water permeablematerial as well as a difference in relative humidity between the twogas streams. These differentials drive moisture from the more humid,higher pressure cylinder through the water permeable material and intothe dry, lower pressure, inner chamber. This behavior is highly ideal.Moisture that inhibits oxygen separation capacity of the adsorbent iseffectively removed prior to entering the sieve bed, thereby maximizinglifetime of the adsorbents. Furthermore, re-hydration of the dry oxygenis necessary before output to the patient thereby preventing patientdiscomfort due to ultra dry oxygen.

The prior art devices employ a variety of techniques to achieve moistureremoval. These techniques include desiccant dryers, membrane filters,centrifugal devices, and the like. The moisture management systemdescribed herein is superior to the prior art techniques. The device ofthe invention is lightweight, low cost, and self-sustaining (i.e., doesnot need to be replaced during the lifetime of the concentrator).Furthermore, unlike membrane filters, the water-permeable material isimpervious to nitrogen and oxygen, thus no undesirable nitrogen mayenter the product stream. The water-permeable barrier comprises amaterial that shows high selectivity for moisture yet is not permeableto gases. This material may contain a hydroscopic adsorbent material,such as aluminum oxide, silica gel, and the like and combinationsthereof, and may or may not include a binder. The material may be anextrudate, a casting, a sintered material, or an otherwise formedstructure. Furthermore, the material may be incorporated within thewalls of a barrier that is non-permeable to air or sealed within thewalls of an existing barrier constructed from a material that isnon-permeable to air. A functional grading of deliberate design withinthe walls of the adsorbent material may also be incorporated to furtherensure non-permeation of gases.

The water-permeable barrier is highly unique in that it also serves as a“getter” material, or moisture sink, that acts to attract moisture fromthe product end, the sieve bed valves, and the valve manifold and anydry interconnections. Upon shutdown, the getter material sequesters anymoisture remaining in or entering the system.

The moisture management system also serves as a pulse control system andacts as an oxygen reservoir.

In certain embodiments, the use of aluminum as the outer cylinder 27promotes heat dissipation thereby maintaining maximum adsorptioncapacity in the sieve bed and aiding in the condensation and attractionof moisture in the feed stream to the water-permeable material.

The outer chamber material is impermeable to both water and gases. Theinner chamber material is impermeable to gases yet highly permeable towater.

Configuration of the moisture management system within the device hasbeen described with a multiple container arrangement as depicted in FIG.11 to have a greater impact upon moisture removal, however the devicecould similarly function with a single container.

Pressure swing adsorption (PSA) devices using zeolites have been usedfor many different separation applications of gases or liquids includingthe separation of air to produce medical grade oxygen. Many of thesesystems use hundreds or thousands of grams of zeolites depending on theapplication. Hundreds of grams of zeolites are used intwo-zeolite-containing-column-separation systems designed to produceoxygen for long-term home applications. Moisture in the compressed airentering these air-separation systems is not typically a problem sinceone column is being used for air separation while the other is beingregenerated and the cycle time between the columns is on the order ofminutes.

The portable rapid cycle pressure swing air separation devices of theinvention produce medical grade oxygen with a cycle time ofapproximately one-second between the advanced molecular sieve-containingbeds. The unit is specifically designed as a light-weight portablesystem and uses only about 10 to 20 grams of a zeolite specificallydesigned for use in this rapid cycle system. Since small quantities ofadvanced molecular sieve materials (especially zeolites) are used inthis system, precautions are utilized to both minimize the amount ofmoisture permitted to enter the zeolite columns and to protect themolecular sieve material from moisture entering the system from the airentrance port or through the oxygen exit port when the system is not inuse.

A method for the simultaneous drying and humidifying of two separate gasstreams in a PSA oxygen concentrator is described. Incoming feed airdirected into a chamber containing, for example, coaxial tubes, theinner being comprised of a non-porous material with propensities towardswater adsorption, surrenders moisture which then migrates through theadsorbent to the outgoing dry gas. Furthermore, the method allows for amoisture sink during periods of non-operation. The prior art containsmany references to moisture removal. These techniques include desiccantdryers, membrane filters, centrifugal devices, etc. The moisturemanagement system described is superior to past techniques. It islightweight, low cost, and self-sustaining (does not need to be replacedduring the lifetime of the concentrator). Furthermore, unlike membranefilters, the water-permeable material is impervious to nitrogen andoxygen, thus no undesirable nitrogen may enter the product stream.

In certain embodiments, the process used to minimize the moistureentering the portable oxygen concentrator utilizes adrying/re-moisturizing component located after the air compressor andprior to the adsorbent beds. The drying/re-moisturizing apparatuscontains two co-axial container systems (two moisture control unitcomponents 24 shown in FIG. 11 as (A) and (B), for example, as aco-axial tubular design). The containers 24 are sealed near the endsproducing an outer chamber 27 and an inner chamber 28. Each containerhas an entry port 45 and exit port 46. The outer container wall isnon-permeable to air or moisture with the entry port located near oneend of the container and connected to the compressor 2 (not shown inFIG. 11). The outer chamber wall is fabricated from a lightweight metal,such as aluminum, which also serves to dissipate heat of compression andenhance condensation of moisture within the chamber for both co-axialsystems A and B. The moist compressed air is introduced through theentry port of the first co-axial container system (A), passes throughthe outer container chamber 27, and leaves through the exit port 46 ofthe outer chamber. During this passage, moisture is removed from the airstream as discussed below. The compressed air then flows through theouter container of an identical co-axial container system (B) where themoisture content is further reduced and the air then enters the zeolitecompartment (C) where it is separated into an oxygen stream and anitrogen stream.

Function of the moisture permeable membrane is enhanced by two featuresof operation: a pressure and moisture differential across the material.

An additional barrier to protect against incoming moisture may beincorporated directly into the sieve bed in the form of a guard layer.The guard layer may contain adsorbents with high propensities formoisture uptake similar to those used to form the inner wall of themoisture uptake chambers. The adsorbents may be chemically or physicallysequestered within fibrous forms to prohibit a mixing with thoseadsorbents responsible for oxygen separation.

The walls of the inner chamber 28 of co-axial systems (A) and (B)comprise a getter material, which is non-permeable to air but permeableto moisture and preferably comprises an adsorbent fabricated within thewalls of the container. The adsorbent located in the walls of the innerchamber 28 (a “getter” for moisture) can be (1) incorporated within thewalls of a container that is non-permeable to air, (2) sealed within thewalls of an existing container constructed from a material that isnon-permeable to air, and/or (3) a container produced from an extrudedadsorbent permeable to moisture but non-permeable to air. The adsorbentmay be aluminum oxide, silica gel, or others obvious to those trained inthe art. The extruded inner container walls may be of tubular shape orother designs, for example, a star-shaped tube or other designs thatmaximize the surface area exposed to the moist compressed air. As moistair passes through the outer container it contacts the wall of the innercontainer. The adsorbent in the inner container wall sequesters moisturefrom the compressed air. Two factors enhance moisture transfer from theouter container to the inner container in co-axial systems (A) and (B).The first is that the compressed air pressure in the outer chamber 27 ismuch higher than the pressure in the inner chamber 28. The second isthat the oxygen product stream passing through the inner container ofco-axial system (A) is dry and is readily re-moisturized and themoisture is carried away with the product stream. The nitrogen streamleaving sieve bed (C) and passing through the inner container ofco-axial system (B) has a lower moisture content than the compressed airpassing through the outer container of (B) and moisture is carried awaywith the nitrogen produced. Both of these factors enhance moistureremoval from the compressed air and provide a re-moisturized oxygenproduct for inhalation thereby preventing patient discomfort due toultra-dry oxygen.

Adsorbents are preferably utilized in the moisture control unit 24.However, membranes may be used for the drying apparatus such as the onedescribed above. However, the membranes can permit passage of somenitrogen through the membrane and dilute the medical grade oxygenproduct passing through the inner container of co-axial system (A). Themoisture control unit may contain bacteria-suppressing materials, suchas colloidal silver.

The second co-axial container system (B) not only further reduces themoisture content of the compressed air but also serves as a “moisturegetter” for moisture that may enter the portable rapid cycle pressureswing air separation system when it is not in use. By using a co-axialdrying system on the advanced molecular sieve bed inlet and outlets,upon shutdown, the device sequesters moisture from any air entering thedevice through the air stream entrance or from moisture entering thedevice through the oxygen and nitrogen exit ports.

The second moisture management approach is to make the sieve beds easilyreplaceable by the user. V-Box Inc. has a belt wearable concentratorthat has separate pouches for compressor, sieve beds, and batteries.This makes the sieve beds replaceable, but only as a separate unit andit requires making 8 pneumatic connections, each with a length of tubingthat introduces sizeable flow restrictions. As described herein, in oneembodiment, sieve bed architecture has been developed that has onlythree pneumatic connection points, is very simple to replace, and ishermetically sealed until it is inserted into the oxygen concentrator.Rupture plates preferably cover the ports. These plates are piercedautomatically when the sieve module is inserted into the concentratorbody. A moisture control unit may be attached to the sieve module sothat both the adsorbent bed and filter are changed at the same time. Invery moist environments, the adsorbent bed may require more frequentchanging, but in general it should last for several months. Theadsorbent-filter module is as easy to change as the battery pack. Theadsorbent bed-filter pack is preferably stored and/or sold housed in amoisture impenetrable pouch or container.

Battery Pack for Portable Oxygen Concentrator

Conventional portable oxygen concentrators deal with additional run-timeby various methods. For example, the AirSep “Freestyle” unit offers abattery belt (“AirBelt”) for additional run-time beyond the internalbattery pack. But the belt is worn by the user and attached to thedevice through a power cord. Respironics (“EverGo”) has two batterycompartments allowing the user to double their available run-time byinserting one additional battery pack. The battery weight goes up byincrements of 1 battery pack (each approximately 1.5 lbs).

U.S. Pat. No. 7,510,601 discloses the use one or more batteries mountedexternally on the portable oxygen concentrator. It is common practicefor other portable battery operated devices (e.g. cordless drills, saws,etc.) to mount the battery pack externally to the device. For example,U.S. Pat. No. 3,952,239 and U.S. Pat. No. 6,515,451 describe variousbattery operated tools with interchangeable battery packs. A moreflexible approach to battery utilization is used in the variousembodiments of the present invention.

A problem with portable oxygen concentrators is the balance betweenbattery weight and available run-time of the unit. This approach is toallow for a flexible battery pack with minimum impact on the size/weightand available space utilized by the ultra rapid cycle portable oxygenconcentrator.

In certain embodiments, the battery pack for the ultra rapid cycleportable oxygen concentrator are incorporated as part of device, yetremovable, and take up less volume, than a device that has a housingthat the battery pack is inserted into. In many embodiments, the generaloverall volume is less, since no battery compartment is required. Also,since the pack may be mounted outside on the case, the different batterypacks may have the same general shape, conforming to the overall devicedesign, but can have different mass or weights that allow for differentquantities of battery cells. Without having the constraint of thehousing within the device, the battery pack can conform to the overallshape and design of the device, rather than the battery pack appearingto be a separate component mounted to the device.

Allowing for different battery packs gives the user a flexibility ofchoosing how much run-time vs. weight carried. If the user is going tooperate the unit for an extended period when there might be unknownaccess to battery charging, the user could opt for the longer run-time,yet heavier battery pack. The lighter pack could be chosen for quicktrips or where weight might be more of an issue (such as whileexercising). Illustrated below, this embodiment would allow for weightincrements of 0.5 pounds or the weight of a grouping of battery cellssufficient to supply the desired voltage.

FIGS. 6A, 6B, and 6C are back, top and bottom views, respectively, ofthe battery pack configured with 15 cells (8 on top layer, 7 on bottomlayer).

FIG. 7 is an exploded perspective view of the 15 cell battery pack 40with the battery cells 34, protection circuit module (PCM) unit 36, andback plate 37 of the battery pack case 35.

FIGS. 6 and 7 illustrate an embodiment of the battery pack according tothe principles of the current invention. The battery pack case 35 may beshaped to conform to the overall exterior style of the device, and maynot be housed within the device, but mounted to appear as part of thedevice. This embodiment shown in FIGS. 6 and 7 utilizes a curved shapethat mimics the overall design of the portable oxygen concentrator. Theinclusion of the battery pack 40 on the device completes the shape anddesign of the portable oxygen concentrator 43. Battery cells 24 arearranged within the case 35 to conform to the general curved shape ofthe case, filling the available area, and secured to the case throughtabs 41 above and below the battery cells 34. Space unfilled bybatteries (or wiring, connectors or the PCM) can be left open, or filledwith foam.

Recessed female connectors for the positive and negative terminals 42may be on the battery pack 40 illustrated in FIG. 6C, the connectors maybe blade style or other quick release connector type.

FIG. 7 shows the arrangement of the battery pack case 35, battery cells34, a protection circuit module (PCM) 36 is incorporated within thebattery pack for over and under charge protection, and the back plate37, which is where the guide rail can mate with a corresponding channelon the device case.

FIG. 8 is a side view of a portable oxygen concentrator system having abattery pack module 40 and the remainder of the portable oxygenconcentrator module 43 where the battery pack handle 38 conforms to theportable oxygen concentrator's handle 39 to make it appear as acontiguous piece. The portable oxygen concentrator module 43 has a firstpartial handle portion 39. The battery pack module 40 has a secondpartial handle portion 38. The battery pack module 40 releasablyconnects to the portable oxygen concentrator module 43. The firstpartial handle portion of the portable oxygen concentrator module 43 andthe second partial handle portion align to form a single integratedhandle. The second partial handle portion 38 may be used to attach andremove the battery pack to and from the device.

The battery pack may be fastened to the remainder of the portable oxygenconcentrator portion device through a quick release latch and have aguide rail on the mating surface side which aids in aligning the packwhile it is mounted onto the portable device (not shown in FIG. 8).

In certain embodiments, the battery pack 40 has the same height, butallows for variation in overall volume, width and depth, and hasdifferent quantities of secondary battery cells wired to deliver thesame voltage. The varying quantity of battery cells gives theflexibility of more power and run-time (but heavier weight), or lessrun-time (but lighter weight), while still conforming to the overallshape of the battery pack 40. FIG. 7 illustrates the design that allowsfor two rows high of battery cells.

In certain embodiments, the battery cells may be grouped and wired inseries and the groups arranged and wired in parallel to deliver thenecessary voltage and power. For example, an 18.5 V battery pack usingrechargeable lithium ion battery cells (2600 mAhr 18650 cells) wouldhave five 3.7 V cells wired in series to give 18.5V, 2 or more of thesegroups wired in parallel together give additional power. The group offive cells has the maximum capacity of 2.6 Amp-hours, wiring additionalgroups in parallel increases the available power. Two groups would yield5.2 A-hrs, 3 groups would supply 7.8 A-hrs. A 5 cell series-set weighsapproximately 0.5 pounds, two groups would weigh approximately 1 pound,and longer run-time packs would increase in increments of approximately0.5 pound.

In certain embodiments, the battery cells may be grouped in a series of3, 4, 5 or more cells to yield the desired voltage. Groups of thesecells may be wired together (and to the PCM) in groups of one or more toyield the desired power capacity.

Selection criteria of the battery cells includes lightweight with highenergy density, including but not limited to: lithium ion,lithium-polymer, silver-zinc, or other rechargeable battery cells.

Oxygen Sensor for Portable Oxygen Concentrator

Oxygen concentrators typically include a sensor for measuring oxygenpurity and a way to alert the patient should purity dip below 85%.Portable oxygen concentrators typically use an electrochemical sensor(also galvanic cell, and micro-fuel cell type sensors). Such sensorsprovide an electrical voltage signal linear to oxygen purity. Thevoltage results from a chemical reaction between sensor materials andoxygen passing into the sensor. Somewhat like a battery, over time thesignal changes as sensor electrolytes are consumed. This reactionaccelerates in high (85%+) oxygen conditions present in portable oxygenconcentrators.

Electrochemical advantage/disadvantage. This sensor requires very lowpower (less than 0.1 watt), needed only for an auxiliary circuitproviding signal analysis (comparison with minimum acceptable oxygenlevel) and LED status display. The signal is linear to oxygen purity.Sensor warm-up is not required. However, the sensor has a short lifetime(a few months to a year from date of manufacture, even when stored),especially in high purity oxygen environment, requires periodicrecalibration, and may require periodic replacement. The accuracy isabout 2% to 5%.

Home stationary oxygen concentrators have fewer limitations on powerconsumption and therefore may use a long lifetime zirconium based oxygensensor. Such sensor technology is a spin-off from the automobileindustry. This sensor requires more power due to a heater and operationat 450° C. The output current is non-linear to oxygen purity. Forexample, the Fujikura FCX-UWC zirconium based sensor is designed forcontinuous 75% to 95% oxygen purity, output is 8 to 20 micro-amp, withthe heater consuming 1.5 watt.

Zirconium advantage/disadvantage. This sensor has a long lifetime(10,000 hours, actual operation), never needs recalibration, and neverrequires replacement. Accuracy is 1%. However, it requires large power(1.5+ watt), and a long (4.5 minute) warm-up time followed by a (0.5minute) settling time.

In view of the advantages and disadvantages noted above, a need hasarisen for a long lifetime oxygen sensor suitable for portable oxygenconcentrators. The zirconium based sensor is a good candidate if onlythe power consumption could be reduced.

In one embodiment, the zirconium-based oxygen sensor is operated withless power, which permits the sensor to be used in a portable oxygenconcentrator of the invention. The method involves intermittentoperation and pulse-width modulation of the sensor's heater control.Using these new methods, the average power is reduced to about 10% toabout 20% of normal.

The zirconium based oxygen sensor electronic controls are shown in FIG.9 and timing is shown in FIG. 10. The oxygen sensor conserves power bybeing turned off when an oxygen reading is not required. Typically, themicrocontroller orchestrates a reading at 10 minutes after startup ofthe concentrator, and after another 30 minutes. Thereafter readings maybe taken as infrequently as once each hour.

Each oxygen reading involves several steps carried out over a 5 minuteperiod. This begins with a 4.5 minute warm-up to 450° C., followed bysufficient time for the signal to settle, followed by capture of thereading, and analysis. Heating of the sensor is handled by themicrocontroller via a periodically applied pulse width modulation (PWM)signal to the solid state relay. The PWM is varied by frequency and/orduty cycle. The sensor's current output is converted to a voltagesignal, amplified, and then input by the microcontroller's comparator.That reading is compared to a voltage set-point representing 85% oxygenpurity. When the sensor reading is above set-point then the LED foroxygen purity ok is lighted. In case the oxygen level dips below 85%,the microcontroller firmware alerts the patient by flashing the LEDand/or sounding an alarm. In the extreme case of persistent low oxygenlevels, the microcontroller can initiate complete shutdown of theconcentrator.

The above described method translates to an average power consumption of0.2 watts for the zirconium based oxygen sensor compared with 2 wattsfor continuous operation. This value assumes 5 minutes operation eachhour (that is, 5 min/60 min×2 watt=0.2 watt on average). This is anacceptable power level for the oxygen sensor, because the rest of theconcentrator, depending upon oxygen setting, requires about 20 watts toabout 50 watts.

Optional Features of Portable Oxygen Concentrator

The device may also comprise:

-   -   a source of a fluid mixture comprising at least a first        component and a second component;    -   a collector of said first component;    -   a collector of an exhaust fluid stream enriched in said second        component and depleted in said first component;    -   an fluid induction unit.    -   a data collection component;    -   a user interface component; and/or    -   a vacuum unit.

The sorption device may further comprise valves, including mechanicalcheck valves, Tesla valves, and pneumatic diode valves, althoughadditional valves are not preferred.

Docking Station

In an alternate embodiment, the portable oxygen concentrator may be partof a system where the portable oxygen concentrator may be removed by theuser (for example, when a stationary unit is available or whensupplemental oxygen is not needed) and placed in a docking station witha battery recharge to recharge the battery cell(s).

The methods, devices, and systems of the invention may be microprocessorcontrolled. The adsorption devices of the invention may comprise atleast one power conditioning device. Suitable power conditioning devicesinclude a voltage changing device (such as a piezoelectric transformeror a high frequency transformer), a poly-phase frequency generator, apoly-phase frequency amplifier (a power transistor, a complimentarymetal oxide semiconductor (CMOS), an insulated gate bipolar transistor(IGBT)), or a combination thereof.

Since the devices and systems of the invention are used forconcentrating oxygen for medical use, the devices and systems maypreferably be small enough in size and weight to be easily carried by anelderly person or an individual with compromised health. The devices orsystems may be supported by a purse-like or “fanny pack”-type holderwith a shoulder strap.

When used for supplying medical oxygen, the device may further comprisea muffler to dampen noise, an optional cannula, and/or an optionalconserver. The cannula may be held by, contained in, or hidden by theshoulder strap described above. The conserver that may be usedpreferably senses inspiration and either opens a valve admitting oxygento the cannula, or the sensor controls the cycle time of the portableoxygen concentrator.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention andspecific examples provided herein without departing from the spirit orscope of the invention. Thus, it is intended that the present inventioncover the modifications and variations of this invention that comewithin the scope of any claims and their equivalents.

EXAMPLES

The present invention is further defined in the following Examples, inwhich all parts and percentages are by weight and degrees are Celsius,unless otherwise stated. It should be understood that these examples,while indicating preferred embodiments of the invention, are given byway of illustration only. From the above discussion and these examples,one skilled in the art can ascertain the essential characteristics ofthis invention, and without departing from the spirit and scope thereof,can make various changes and modifications of the invention to adapt itto various usages and conditions.

Example 1

Performance of regenerated adsorbent output of oxygen at high levels ofrelative humidity (at 75% relative humidity) was measured. The data isshown in FIG. 13. As can be seen in FIG. 13, at 75% relative humidityfor input air, oxygen production remains above an 88% purity level for aperiod of 22 days of continual operation (equivalent to approximately 65patient operation days). No moisture removal technology was incorporatedinto the testing regime in order to obtain a baseline of adsorbentperformance.

Example 2 Cycle Time Selection for Adsorbent Bed

Tests were conducted using an 18 mm diameter, 76 mm long adsorbent bedthat holds approximately 12 grams of the advanced adsorbent. The goal ofthese tests was to determine the cycle time that leads to the highestpossible efficiency. In order to do this, the flow rate of air into thebed and the flow rate of the oxygen-enriched product out of the bed weremeasured, in order to calculate the productivity (also known as recoveryrate) of the bed. Productivity is calculated as follows:

$P = \frac{Q_{oxygen} \times O_{2}{Purity}}{Q_{air} \times 0.209}$

Where P is productivity, Q_(oxygen) is the flow rate of oxygen, O₂Purity is the decimal purity of Oxygen, and Q_(air) is the flow rate ofair, which is multiplied by 0.209 (the nominal oxygen purity ofatmospheric air) to obtain the amount of oxygen in the air that passedthrough the bed. In this case, a cycle of 0.78 seconds duration produces0.8 LPM of high purity (95% for the duration of the test) oxygen, whilerequiring approximately 10 LPM of air input. This meets the requirementsset out for the portable medical oxygen concentrator of the invention.The results are shown in FIG. 14.

Example 3 Adsorbent Bed Dimensions (Length/Diameter Ratio) and Quantityof Adsorbent

Several different sizes of adsorbent bed were tested to determine theproper dimensions for a bed to be used with the advanced adsorbent.

Length Diameter Mass Ads Max Output (mm) (mm) L/D ratio (g) (LPM) 76 164.75 9.2 0.6# 101 16 6.31 12.2 0.74* 114 16 7.125 13.8 0.8* 76 18 4.2211.6 0.8{circumflex over ( )} *= requires a pressure input of 270 kPaabsolute {circumflex over ( )}= requires a pressure input of 225 kPaabsolute #= requires a pressure input of 250 kPa absolute

From the results of the tests, it can be shown that an L/D ratio of 4.22worked the best in terms of energy efficiency because it requires lesspressure to produce adequate output.

An additional consideration that affects the size of the adsorbent bedis the amount of time it is able to operate until it must be replacedbecause the performance has degraded due to water adsorption. It ispossible to use 4 adsorbent beds that hold less than one gram ofadsorbent, cycle them at 3-4 cycles per second, and produce the targetedoutput of 0.75 LPM of 85%+ oxygen, but they last for less than one daybefore they must either be replaced or regenerated by heating them andpassing a dry purge gas through them to carry away the water that isliberated. FIGS. 15 and 16 show the degradation curves (at 60% relativehumidity) for one adsorbent bed that holds less than one gram ofadsorbent (FIG. 15), and for one adsorbent bed that holds approximately10 grams of adsorbent (FIG. 16).

Example 4 Maximum Cycle Rates

The maximum possible cycles rates while still achieving at least 85%purity of oxygen were determined using the advanced adsorbents employedin the invention. The results are shown in FIG. 17. A plot showing themaximum cycle rate (in Hz) as a function of adsorbent mass (in grams)achieving at least 85% oxygen purity is presented in FIG. 17.

Example 5 Gas Flow

Function of the moisture permeable membrane is enhanced by two featuresof operation: a pressure and moisture differential across the material.To demonstrate the transfer of moisture from a moist air stream to a dryoxygen flow under these conditions, tests were performed. Using acontainer prepared with non-optimized adsorbent walls, moist air withrelative humidity (RH) of 60% was introduced into the outer container asultra-dry oxygen (RH=<0.1%) was concurrently flowed through the innerchamber. A pressure differential of 10 psi was maintained throughout theexperiment along with a ten-fold decrease in flow between the moist anddry gas streams. After equilibrium was achieved, RH of the moist airdecreased by 32% while the moisture level of the dry oxygen increased to7%. The purity level of oxygen was unaltered during the experimentthereby confirming the impervious nature of the adsorbent material togases.

When ranges are used herein for physical properties, such as molecularweight, or chemical properties, such as chemical formulae, allcombinations, and subcombinations of ranges specific embodiments thereinare intended to be included.

The disclosures of each patent, patent application and publication citedor described in this document are hereby incorporated herein byreference, in its entirety.

Those skilled in the art will appreciate that numerous changes andmodifications can be made to the preferred embodiments of the inventionand that such changes and modifications can be made without departingfrom the spirit of the invention. It is, therefore, intended that theappended claims cover all such equivalent variations as fall within thetrue spirit and scope of the invention.

What is claimed is:
 1. A portable oxygen concentrator system,comprising: a housing; at least one removable adsorbent cartridge; acompressor; a manifold to control as flow into and out of said removablemodule; a removable battery pack; wherein said battery pack is capableof accommodating a variable number of battery cells without changing theshape of said portable oxygen concentrator system; and wherein saidbattery pack is external to said housing and conforms to and completesthe overall shape of said portable oxygen concentrator system whereinsaid at least one removable adsorbent cartridge comprises: at least oneadsorbent bed; wherein said adsorbent bed comprises at least onemolecular sieve material; wherein said molecular sieve material has asubstantially spherical shape; wherein the ratio of the length of saidadsorbent bed to the diameter of said adsorbent bed is less than about4.8:1; and wherein said adsorbent bed is capable of a ratio of productflow rate to mass of said molecular sieve material of greater than 3.3ml/min/g.
 2. A portable oxygen concentrator system of claim 1, furthercomprising: at least one battery cell.
 3. A portable oxygen concentratorsystem of claim 1, wherein said battery pack comprises: a battery packcase; a plurality of tabs for securing said battery cells in saidbattery.
 4. A portable oxygen concentrator system of claim 3, whereinsaid battery pack case, further comprises: a back plate.
 5. A portableoxygen concentrator system of claim 3, wherein said battery pack case,further comprises: a protection circuit module unit.
 6. A portableoxygen concentrator system of claim 1, further comprising: a moisturecontrol unit.
 7. A portable oxygen concentrator system of claim 1,further comprising: an oxygen sensor.
 8. A portable oxygen concentratorsystem of claim 1, further comprising: a muffler connected to saidmanifold.
 9. A portable oxygen concentrator system of claim 1, furthercomprising: a cannula.
 10. A portable oxygen concentrator system ofclaim 1, further comprising: a conserver.
 11. A portable oxygenconcentrator system of claim 1, further comprising: a docking station;and a battery recharger.
 12. A portable oxygen concentrator system,comprising: at least one removable module comprising a housing; at leastone adsorbent bed contained in said housing; wherein said adsorbent bedcomprises at least one molecular sieve material; wherein said molecularsieve material has a substantially spherical shape; wherein the ratio ofthe length of said adsorbent bed to the diameter of said adsorbent bedis less than about 4.8:1; and wherein said adsorbent is capable of aratio of product flow rate to mass of said molecular sieve material ofgreater than 3.3 ml/min/g; a compressor; a manifold to control gas flowinto and out of said removable module; and at least one removablebattery pack; wherein said portable oxygen concentrator system weighsless than about 5 kg.
 13. A portable oxygen concentrator system of claim12, wherein said at least one removable module comprises one adsorbentbed.
 14. A portable oxygen concentrator system of claim 12, wherein saidat least one removable module comprises two adsorbent beds.
 15. Aportable oxygen concentrator system of claim 12, wherein said molecularsieve material has a mass less than about 50 g.
 16. A portable oxygenconcentrator system of claim 12, wherein said molecular sieve materialcomprises zeolite.
 17. A portable oxygen concentrator system of claim12, wherein said molecular sieve material comprises a metal-exchangedzeolite.
 18. A portable oxygen concentrator system of claim 12, whereinsaid metal-exchanged zeolite is Li⁺-exchanged zeolite.
 19. A portableoxygen concentrator system of claim 12, wherein said adsorbent bed has alength of no greater than about 12 cm.
 20. A portable oxygenconcentrator system of claim 12, wherein said adsorbent bed has adiameter of no greater than about 2.5 cm.
 21. A portable oxygenconcentrator system of claim 12, wherein said removable module isreplaceable by a user.